Similarities and differences between augmentation index and pulse wave velocity in the assessment of arterial stiffness.
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We investigated whether there was a correlation between the simultaneous assessments of augmentation index (AI) and pulse wave velocity (PWV), undertaken by the SphygmoCor system, and what were the principal factors responsible for differences in these two putative assessments of arterial stiffness, in 105 offspring (41 men, 64 women) aged 19-71 years, of patients with familial hypertension. Arterial stiffness was measured using the SphygmoCor pulse wave analysis system. AI and PWV correlated significantly and positively (r = 0.29, p < 0.005) and the strength of the correlation was greater when each gender was examined separately. This led us to observe several-fold higher AI in women (22.04 +/- 12) than in men (8.59 +/- 13) (p < 0.001); the difference could be explained only in part by an inverse regression correlation between AI and height (r = -0.45; p < 0.001), but not PWV. AI was also more influenced than PWV by heart rate and blood pressure. AI is strongly correlated with a previously validated estimate of arterial stiffness, PWV. It is probable that separate normal ranges should be established for men and women, while further studies determine what parameters other than height are responsible for the gender difference. (+info)
Time-dependent pressure distortion in a catheter-transducer system: correction by fast flush.
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BACKGROUND: Distortion of the pressure wave by a liquid-filled catheter-transducer system leads most often to an overestimation in systolic arterial blood pressure in pulmonary and systemic circulations. The pressure distortion depends on the catheter-transducer frequency response. Many monitoring systems use either mechanical or electronic filters to reduce this distortion. Such filters assume, however, that the catheter-transducer frequency response does not change over time. The current study aimed to study the changes with time of the catheter-transducer frequency response and design a flush procedure to reverse these changes back to baseline. METHODS: An in vitro setup was devised to assess the catheter-transducer frequency response in conditions approximating some of those met in a clinical environment (slow flushing, 37 degrees C, 48-h test). Several flush protocols were assessed. RESULTS: Within 48 h, catheter-transducer natural frequency decreased from 17.89 +/- 0.36 (mean +/- SD) to 7.35 +/- 0.25 Hz, and the catheter-transducer damping coefficient increased from 0.234 +/- 0.004 to 0.356 +/- 0.010. Slow and rapid flushing by the flush device built into the pressure transducer did not correct these changes, which were reversed only by manual fast flush of the transducer and of the catheter. These changes and parallel changes in catheter-transducer compliance may be explained by bubbles inside the catheter-transducer. CONCLUSIONS: Catheter-transducer-induced blood pressure distortion changes with time. This change may be reversed by a manual fast flush or "rocket flush" procedure, allowing a con. stant correction by a filter. (+info)
Socioeconomic status and blood pressure reactivity in healthy black adolescents.
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Adolescents in low-socioeconomic-status environments are more susceptible to illnesses, such as hypertension and cardiovascular diseases. This study examined the influence of both neighborhood- and family-level socioeconomic status (SES) on blood pressure (BP) reactivity in a healthy sample of 76 black adolescents. It was hypothesized that a higher level of parental education and/or income would reduce the elevated BP reactivity associated with living in poorer neighborhoods. Census-derived data were obtained using each participant's address. Neighborhood level of SES was based on percentage of households below the poverty line, female-headed households, owner-occupied housing, percentage vacant housing, and average number of persons per household. Family level of SES was based on self-reported level of parental education and annual family income. Adolescents participated in a competitive video game to establish their BP reactivity scores. As predicted, adolescents who lived in poorer neighborhoods had lower diastolic BPs if their parents were more (versus less) educated (P<0.05; 7+/-8 versus 13+/-6 mm Hg). Adolescents who lived in poorer neighborhoods also had significantly lower diastolic BP reactivity (P<0.05) if their family had a higher (versus lower) annual income (7+/-7 versus 12+/-8 mm Hg). These data are the first to demonstrate the buffering effect of family SES on the negative health consequences of living in low-SES neighborhoods in healthy black adolescents. (+info)
A simplified paired neck chamber for the demonstration of baroreflex blood pressure regulation.
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In this investigation a simplified variable-pressure paired neck chamber was developed as a practical alternative to traditional neck collar designs used to study the arterial baroreceptor reflex in humans. The purpose of this new design was to extend the use of the noninvasive neck chamber method of baroreceptor investigation to teachers of physiology. Performance tests indicate that these new chambers are capable of delineating the stimulus-response relationship for both the blood pressure baroreflex [sensitivity = 0.425 +/- 0.13 mmHg mean arterial pressure (MAP)/mmHg neck chamber pressure (NCP); range = 24.9 +/- 4.6 mmHg MAP] and the heart rate baroreflex (sensitivity 0.273 +/- 0.12 beats.min-1.mmHg NCP-1; range = 16.7 +/- 6.8 beats/min). This was achieved by applying localized positive and negative air pressures to the carotid sinuses throughout the range from +60 to -60 mmHg in steps of 20 mmHg. This simplified neck chamber method offers distinct methodological advantages over traditional neck collars, making it a valuable tool for demonstrating baroreflex regulation of the circulation. (+info)
Blood pressure exceeding national guidelines among women after stroke.
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BACKGROUND AND PURPOSE: After a transient ischemic attack or stroke, the risk for recurrence may be reduced by treatment of hypertension. The purpose of this study was to determine how commonly blood pressure exceeds national guidelines among patients who have had one of these events. METHODS: Subjects were 644 women participating in a randomized trial of estrogen for secondary stroke prevention. We measured blood pressure 1 month after the stroke or TIA while patients were under the care of their personal physicians. Among 536 patients, a second measure was made at an average of 2.9 years after the first. RESULTS: The mean age of participants was 71 years, and 73% reported a history of hypertension. At baseline, only 44% (280/644) of the women had blood pressure values within national guidelines (<140/90 mm Hg). With separate guidelines used for diabetics (<130/85 mm Hg) and nondiabetics (<140/90 mm Hg), the proportions of women within the guidelines were 27% and 44%, respectively. Overall, 39% of patients were within the diabetes-adjusted guidelines. Among patients whose blood pressure exceeded 140/90 mm Hg at first examination, 55% were still in excess at follow-up. Features associated with severe hypertension at first examination (>160/100 mm Hg) were history of hypertension, education less than college, and higher cognitive functioning. CONCLUSIONS: Blood pressure values in excess of national guidelines are common after stroke and TIA, especially among diabetic patients. Efforts to lower blood pressure control may enhance secondary prevention. (+info)
Control of blood pressure and risk of stroke among pharmacologically treated hypertensive patients.
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BACKGROUND AND PURPOSE: Despite improved control of blood pressure during the last decades in the United States, a considerable proportion of treated hypertensives have not achieved target blood pressure levels. We estimated the proportion of strokes occurring among treated hypertensive patients that may be attributable to uncontrolled blood pressure. METHODS: A population-based case-control study was conducted among treated hypertensive members of Group Health Cooperative of Puget Sound. Cases were treated hypertensive patients who sustained a first fatal or nonfatal, ischemic (n=460) or hemorrhagic (n=95) stroke during 1989-1996. Controls were a random sample of stroke-free, treated hypertensive Group Health Cooperative enrollees (n=2966), similar in age to the stroke cases. Multiple measurements of blood pressure and other cardiovascular risk factors were collected from medical records. Logistic regression was used to estimate the risk of ischemic stroke and hemorrhagic stroke associated with uncontrolled blood pressure, defined as diastolic blood pressure >90 mm Hg or systolic blood pressure >140 mm Hg. The fraction of strokes attributable to uncontrolled blood pressure among treated hypertensives was calculated. RESULTS: Blood pressure was uncontrolled in 78% of ischemic stroke cases, 85% of hemorrhagic stroke cases, and 65% of controls. After adjustment for potential confounders, uncontrolled blood pressure among treated hypertensive patients was moderately associated with ischemic stroke (risk ratio=1.5 [95% CI, 1.2 to 1. 9]) and strongly related to hemorrhagic stroke (risk ratio=3.0 [95% CI, 1.7 to 5.4]). We estimated that 27% (95% CI, 11% to 39%) of the ischemic strokes and 57% (95% CI, 26% to 75%) of the hemorrhagic strokes among treated hypertensive patients were attributable to uncontrolled blood pressure. Overall, 32% (95% CI, 14% to 45%) of all strokes were attributable to uncontrolled blood pressure. CONCLUSIONS: A considerable proportion of incident strokes among treated hypertensive patients may be prevented by achieving control of blood pressure. (+info)
Which parameters of beat-to-beat blood pressure and variability best predict early outcome after acute ischemic stroke?
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BACKGROUND AND PURPOSE: In hypertensive populations, increasing blood pressure (BP) levels and BP variability (BPV) are associated with a greater incidence of target organ damage. After stroke, elevated 24-hour BP levels predict a poor outcome, although it is uncertain whether shorter-length BP recordings assessing mean BP levels and BPV have a similar predictive role. The objectives of this study were to compare the different measures of beat-to-beat BP and BPV on outcome after acute ischemic stroke and assess whether these parameters were affected by stroke subtype. METHODS: Ninety-two consecutive admissions with a CT-confirmed diagnosis of acute ischemic stroke were recruited, of whom 54 had cortical infarction, 29 subcortical, and 9 posterior circulation infarction. Casual and two 5-minute recordings of beat-to-beat BP (Finapres, Ohmeda) were made under standardized conditions within 72 hours of ictus, with mean BP levels taken as the average of this 10-minute recording and BPV as the standard deviation. Outcome was assessed at 30 days as dead/dependent or independent (Rankin +info)
Blood pressure awareness in Austria. A 20-year evaluation, 1978-1998.
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AIM: To evaluate public awareness following a nationwide educational campaign on hypertension. METHODS AND RESULTS: In 1978 the Austrian Heart Foundation conducted a nationwide educational campaign to increase the awareness of the population regarding the importance of recognizing and treating high blood pressure. Following this campaign, five opinion polls of random and representative samples were conducted to measure the awareness and knowledge of the population relating to issues of high blood pressure. The poll results indicated that during the period immediately following the awareness campaign, knowledge and perception of the dangers of high blood pressure increased. However, this effect dissipated during subsequent years. In 1978, 14% of the population were reported to be hypertensive and 10% had no relevant information about their blood pressure status. In 1998, those who labelled themselves as hypertensive dropped to 12%, while those who did not know their blood pressure values, increased to 14%. The percentage of the population who recalled having their blood pressure measured during the last 3 months dropped from 49% in 1978, to 34% in 1993, and remained at 34% in 1998. CONCLUSION: We conclude that the intensive blood pressure education campaign had only a temporary effect on improving blood pressure awareness. Improved strategies are needed to achieve better community control of hypertension. (+info)